Background: Vitamin K may have a protective role against bone loss and osteoporotic fractures associated with aging, although data in humans are inconsistent and the mechanisms involved are still unknown.

• The main objective of the study was to assess the associations between vitamin K intake, bone density, bone structure quality and biochemical bone metabolism markers in elderly subjects. [Note: As people age, destruction tends to overwhelm bone building in the bone ‘turnover’ process.]

• We also analyzed the relationship between changes in vitamin K intake and the evolution of bone quality markers after two years of follow-up.

Methods: Cross-sectional analysis was carried out on 365 elderly subjects, 200 of whom were also included in a 2-year longitudinal follow-up study.

Usual dietary intakes were assessed using a semi-quantitative 137-item food frequency questionnaire (FFQ). Vitamin K intake was estimated using the USDA database. Bone biochemical markers were measured in a subset of 125 subjects.